There is no problem with mutual exclusivity because all of the classes of Occupant are exclusive of the classes of Non-Occupant (and they are exclusive of each other) and all of the classes of Motorist are exclusive of the classes of Non-Motorist (and they are exclusive of each other).
What we are dealing with are two different CLASSIFICATION SCHEMES for Persons. Each scheme has mutually exclusive classes.
To clarify, I am not proposing “to add the person in a MV not in transport to the occupant category, in addition to leaving that person in the non-motorist category. “
I am simply saying a “person in a MV not in transport” is already an occupant. I am proposing adding the text, “Occupants of transport vehicles not in-transport” in the Inclusions Section under 2.2.35 (occupant), just as it is in the Inclusions Section under 2.2.41 (non-motorist).
This will make it clearer to a user that this is intentional. I believe this inclusion was overlooked in the past. A review of the definitions under 2.2.35 (occupant) and 2.2.41 (non-motorist) reveals this is the intent.
As for the study of safety equipment use and countermeasures, I am sympathetic. Rather than trying to change the definition of what people are and their classifications (which could be destructive), why not simply identify and select the subset of persons one wishes to study by their proper name? It appears to me the subset of Persons at interest here are Persons Not in Motor Vehicles. FARS has divided its two Person Levels as in the charts below to address this very issue.
ADDITIONAL CLASSIFICATION SCHEME:
I don’t think it is necessary but one could create a New Additional Classification by People in Motor Vehicles vs. People Not In Motor Vehicles. If this is done, it is important to recognize and observe the difference between these classification terms and already defined terms like Occupant, Non-Occupant, Motorist, Non-Motorist.